FLAG-tagged L expression vector with either WT or alanine substitution at the respective residue within the N-terminal endonuclease domain was used to transfect 293T cells, together with the myc-tagged NP expression vector and LUC-encoded LASV MG RNA. LUC activity was measured and plotted in log scale. Results shown are the average of at least three independent experiments with error bars representing standard deviations. The expression of L (WT or mutant), NP, and GAPDH in the transfected cells was detected by Western blot analysis using anti-FLAG, anti-myc, and anti-GAPDH antibody, respectively.